Question Number 94756 by AshrafNejem last updated on 20/May/20
$$\left.{s}\left.{olution}:\:\mathrm{Q1}\right){a}\right)\:{n}=\frac{{ln}\left({m}/{m}_{\mathrm{0}} \right)}{{ln}\mathrm{0}.\mathrm{5}}\:=\:\frac{{ln}\left(\mathrm{12}/\mathrm{75}\right)}{{ln}\mathrm{0}.\mathrm{5}}\:=\mathrm{2}.\mathrm{64} \\ $$$${N}=\mathrm{N}_{\mathrm{0}} \left(\mathrm{0}.\mathrm{5}\right)^{{n}} \:=\:\mathrm{6}.\mathrm{02}×\mathrm{10}^{\mathrm{23}} \left(\mathrm{0}.\mathrm{5}\right)^{\mathrm{2}.\mathrm{64}} =\:\mathrm{9}.\mathrm{66}×\mathrm{10}^{\mathrm{22}} \\ $$$${A}=\lambda{N}=\mathrm{1}.\mathrm{5}×\mathrm{10}^{−\mathrm{4}} \:×\:\mathrm{9}.\mathrm{66}×\mathrm{10}^{\mathrm{22}} =\mathrm{1}.\mathrm{45}×\mathrm{10}^{\mathrm{19}} \:{Bq} \\ $$
Commented by mr W last updated on 20/May/20
$${maybe}\:{only}\:{you}\:{know}\:{for}\:{which} \\ $$$${question}\:{your}\:{answer}\:{is}.\:{therefore} \\ $$$${please}\:{post}\:{your}\:{answer}\:{in}\:{the}\:{same} \\ $$$${thread}\:{as}\:{the}\:{question}. \\ $$
Commented by MJS last updated on 20/May/20
$$\mathrm{o}\:\mathrm{tempora}\:\mathrm{o}\:\mathrm{mores} \\ $$